German Unexamined Patent Application No. 33 14 899 has already disclosed an electromagnetically actuable fuel injector in which, for electromagnetic actuation, an armature coacts with an electrically energizable magnet coil, and the linear stroke of the armature is transferred via a valve needle to a valve-closure member. The valve-closure member coacts with a valve seat. The armature is not rigidly mounted on the valve needle, but rather is positioned axially movably with respect to the valve needle. A first return spring impinges upon the valve needle in the closing direction and thus holds the fuel injector closed when the magnet coil is in the zero-current, unenergized state. The armature is impinged upon by a second return spring in the linear stroke direction in such a way that in the inactive position, the armature rests against a first stop provided on the valve needle. Upon energization of the magnet coil, the armature is pulled in the linear stroke direction and entrains the valve needle by way of the first stop. Upon shutoff of the current energizing the magnet coil, the valve needle is accelerated by the first return spring into its closed position, and carries the armature along by way of the stop described above. As soon as the valve-closure member encounters the valve seat, the closing motion of the valve needle is abruptly terminated. The motion of the armature, which is not rigidly joined to the valve needle, continues opposite to the linear stroke direction and is absorbed by the second return spring, i.e. the armature oscillates through against the second return spring, which has a much lower spring constant compared to the first return spring. Lastly, the second return spring accelerates the armature again in the linear stroke direction. Similar fuel injectors are known from German Published Patent Application No. 198 49 210 and U.S. Pat. No. 5,299,776.
The fuel injector known from German Unexamined Patent Application No. 33 14 899 is disadvantageous in particular because of the complex configuration, which provides several individual components for the upper and the lower armature stop. As a result, the manufacturing tolerances of the individual components add up to an overall tolerance which has a disadvantageous effect on the switching precision of the fuel injector.